The invention relates to turbomachine blades or vanes made of composite material comprising fiber reinforcement densified by a matrix. The invention relates also to compressor stator segments and turbine nozzle segments incorporating such composite material vanes.
The intended field is that of gas turbine blades or vanes for aeroengines or industrial turbines.
The fabrication of turbomachine blades of composite material has already been proposed. Reference can be made in particular to international patent application PCT/FR2009/052309 filed jointly by SNECMA and SNECMA Propulsion Solide. This application describes the fabrication of a turbomachine blade made of composite material including a fiber reinforcement densified by a matrix. More precisely, this method exhibits the feature that the fiber blank fabricated by three-dimensional weaving is shaped to obtain a one-piece fiber preform having a first portion constituting an airfoil and blade root preform and at least one second portion constituting an inner platform and blade outer platform preform. Thus, after densification of the preform, it is possible to obtain a blade made of composite material having a fiber reinforcement consisting of the preform and densified by the matrix, and forming a single part with integrated inner platform and/or outer platform.
The blade obtained by such a method has the disadvantage that its outer platform cannot integrate both a function of sealing (through the presence of wipers) to the housing which surrounds the blades and an aerodynamic function (by the presence of covering spoilers defining the outside of the flowpath of the gas stream in the turbine).
French patent application No. 09 58931 filed jointly by SNECMA and SNECMA Propulsion Solide, describes the fabrication of a blade made of composite material forming a single part with integrated inner platform and outer platform, the outer platform providing both the sealing function and the aerodynamic function.
However, the fabrication of such an outer platform with the method described in French patent application No. 09 58931 involves in particular shaping and molding operations with two-layer fiber structures, operations which are completely feasible but which can be more complex to carry out than with single-layer structures. In addition, the blade thus fabricated does not incorporate an anti-tilting wall.
Further, in the event of damage to the outer platform of the blade fabricated according to the method described in French patent application No. 09 58931, the aerodynamic function and the sealing function are both impacted because the outer platform is formed in a single part providing both functions.
Use of CMC materials has also been proposed for turbine nozzles, in particular in application WO 2010/146288.
A conventional metallic turbine nozzle or compressor stator is formed of several assembled sectors, each sector comprising an inner platform, an outer platform and a plurality of airfoils extending between the inner and outer platforms and integral therewith. The inner and outer platforms delimit the gas or air flow passage in the turbine nozzle or compressor stator. On the outside, the outer platforms of the segments are formed integrally with legs allowing the mounting of the turbine nozzle or compressor stator in a casing.